serf, or slave

Latin, servus.

Servus, translated as slave in the Phillimore edition, is sometimes rendered as serf.

Slaves formed the fourth largest group among the peasantry, over 10% of
the recorded population and significantly higher than this if allowance
is made for their almost complete omission from the countiesof circuit 6.This omission was certainly a quirk of the Returnfrom the northern circuit since slaves appear in considerable numbers in all other counties, and the one satellitetext for the circuit reveals that there were slaves on the estates recorded there but not in Domesday Book.

Slaves were at the bottom of the economic and social scale, normally
without resources of their own and there to perform their lord's
bidding. The significant correlation between numbers of slaves and plough teamson the lord's demesne, or home farm, has been taken to prove that they were often utilised by the lord as his ploughmen.

There has been some discussion as to whether slaves were recorded as
individuals or as heads of families. If the recorded slaves were all
individuals, they constituted little more than 2% of the population,
since the totals for other groups are normally multiplied by a factor of
4-5 on the assumption that the numbers represent heads of families
rather than individual peasants. These divergent estimates are of real
consequence. The lower figure would certainly help to explain the rapid
disappearance of slavery after the Conquest. However, the most recent
investigations have concluded that slaves were probably counted on the
same basis as other social groups, in which case they formed 10% of the
population. In this case, their virtual disappearance within a
generation of 1086 was a remarkable social transformation aided,
perhaps, by a tendency by lords to endow slaves to perform their
ploughing functions as 'free ploughmen'.

For further information, see M.M. Postan, The famulus: the estate labourer in the XIIth and XIIIth centuries (1954); David Pelteret, Slavery in early medieval England from the reign of Alfred until the twelfth century (1995); and J.S. Moore, 'Quot homines?: the population of Domesday England', Anglo-Norman Studies, vol. 19 (1997), pages 307-34.